1. Field of the Invention
The present invention relates to a loading and unloading station for semiconductor processing installations with a closeable charging opening through which wafer-shaped or disk-shaped objects which are accommodated in a transporting container can be loaded, unloaded and reloaded after removing a closure.
2. Description of the Prior Art
For the purpose of charging semiconductor processing installations, it is known to use so-called SMIF boxes as magazine containers with a relatively small enclosed volume in which wafer magazines can be stored and transported. The box can be placed on an opening mechanism in an enclosure or housing which encloses one or more work stations so as to keep them free of dust. The box and opening mechanism have closing elements which are adapted to one another and which can be opened simultaneously one above the other so that dust particles resting on the outside of the closing elements can be enclosed therebetween when the wafer magazines are lowered into the housing together with the two closing elements. The box itself encloses the opening formed in the housing.
A loading and unloading device according to the German Patent 43 26 309 C1, for example, or a device having another operating sequence serves to remove the magazines from the transporting containers and place them in the processing installation. After the semiconductor wafers are processed, the magazines are transported back in the transporting containers.
The technique of SMIF boxes is especially suited for semiconductor wafers with smaller diameters, as is conventional. In view of the material characteristics of the semiconductor wafers, these SMIF boxes and the wafer magazines used with them are becoming increasingly unsuitable as transporting containers as the diameter of semiconductor wafers increases.
Transporting containers which take over the function of magazines at the same time are already known for semiconductor wafers of this type. Loading, unloading and reloading of the semiconductor wafers is effected individually in a plane parallel to the surface of the semiconductor wafers, wherein the transporting container can be closed by a container cover extending substantially at right angles to the loading and unloading plane. Accordingly, in contrast to the SMIF box, the container cover is removed and inserted laterally rather than in a downward direction.
Since the transporting containers are enclosed by a space with low requirements, as regards cleanness and since there are no magazines which can be loaded and unloaded such as those used in the SMIF technique, the charging of semiconductor processing installations proceeding from these transporting containers and the transporting back from such installations into the transporting containers presents problems. Moreover, the problem is exacerbated in that optional loading and unloading into and out of a greater number of transporting containers must be ensured under certain circumstances and the containers themselves must be supplied and removed by operating personnel under favorably ergonomic conditions.
An arrangement for storing, transporting and inserting substrates is known from EP 542 793 B 1. In this arrangement, a cassette with a lateral closing cap is arranged opposite a loading slot. The cassettes are brought into the loading position one after the other by a lifting plate which can hold a packet of stacked cassettes. When this position is reached, the closing cap is swiveled open at one edge and the substrate wafer is inserted into the clean room by a drawer which can travel out of the cassette. An air flow exiting from the loading slot prevents particles from penetrating into the clean room in that it passes through an open gap between a protruding seal and the cassette.
A significant improvement over the foregoing concepts has been presented in U.S. Pat. No. 5,772,386 to Mages et al., the entire disclosure of which is incorporated herein by reference.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
The present invention relates to a load port module which is mounted adjacent a process tool for loading semiconductor wafers to the process tool and unloading them from the process tool. The module includes a mounting frame having a charging opening therein for entry into the process tool, a platform having an upper surface for supportively receiving a cassette containing the semiconductor wafers to be passed though the charging opening into the process tool, a selectively operable closure movable between a first position withdrawn from the charging opening allowing the passage therethrough of the semiconductor wafers and a second position overlying the charging opening preventing the passage therethrough of the semiconductor wafers, and a shroud movable between a retracted position fully exposing the platform and its associated cassette and an advanced position fully encompassing the platform and the cassette adjacent the process tool. The shroud serves as a barrier against the passage of particulate matter into the process tool. In one instance, the platform includes a tilt assembly for moving a cassette receiving cradle with the cassette thereon from the first location to a second location at the reception region into the process tool such that the plurality of wafers are then supported in a substantially level orientation. In another instance, the platform is movable in plane between a withdrawn position distant from the charging opening and an advanced position proximate the charging opening.
The present invention has resulted from a semiconductor industry requirement for an ergonomic system to safely load cassettes of wafers into processing equipment allowing for transporting and placing the cassettes onto the equipment with the wafers either in the vertical or in the horizontal orientation. In the former instance, the wafer cassettes need to be rotated to the horizontal position for access by standard pick and place robots and this rotation must be accomplished with minimum jarring or abrupt motion to avoid wafer damage or ejection from the cassette. In the latter instance, the wafer cassettes need only be moved from a withdrawn position to an advanced position.
In all instances, the wafers must be protected during processing from fine particulate contamination. Additionally, when the conventional protective cover of the process tool is open, there is a potential human hazard from robotic handling units to which the load port module of the invention attaches. Further, the environment needs to be contained for cleanliness when the cover is open. Accordingly, the load port module of the invention includes an automated door which assures these goals.
A primary feature, then, of the present invention is the provision of an improved loading and unloading station for semiconductor processing installations with a closeable charging opening through which wafer-shaped or disk-shaped objects which are accommodated in a transporting container can be loaded, unloaded and reloaded after removing a closure.
Another feature of the present invention is the provision of such a loading and unloading station which accepts wafers either in a vertical orientation or in a horizontal orientation and, in the event they are in the vertical orientation, carefully rotates them to the horizontal orientation to enable their removal from and replacement into the cassette using conventional robot apparatus.
Still another feature of the present invention is the provision of such a loading and unloading station which employs an automated tilting mechanism for ergonomic handling of wafer cassettes utilizing the acceleration and deceleration curves provided with a 180xc2x0 crank shaft motion.
Yet another feature of the present invention is the provision of such a loading and unloading station which employs a protective shroud to close over wafers preventing contamination during processing while allowing visibility after wafers are loaded.
Still a further feature of the present invention is the provision of such a loading and unloading station in which rotational closure of the shroud does not interfere with process equipment behind the loading station and occupies minimum space.
Yet a further feature of the present invention is the provision of such a loading and unloading station which can mount to a semi-standard SEMI E63 BOLTS-M interface (Box Opener/Loader to Tool Standard) enabling use with the latest equipment designed for 300 mm wafers to be tested or used with alternate wafer sizes.
Still another feature of the present invention is the provision of such a loading and unloading station which provides for the port door to close the mini-environment when the shroud is open for personnel safety and to contain the mini-environment.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings which are incorporated in and constitute a part of this invention, illustrate one of the embodiments of the invention, and together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.